/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlinePartyInterface.h
return the newIOnlinePartyJoinInfoobject
[FString](API\Runtime\Core\Containers\FString) MakeTokenFromJoinInfo ( const [IOnlinePartyJoinInfo](API\Plugins\OnlineSubsystem\Interfaces\IOnlinePartyJoinInfo) & JoinInfo ) const